Y. Ishibe et al., PROSTAGLANDIN E-1 ANTAGONIZES HYPOXIC PULMONARY VASOCONSTRICTION BUT REDUCES SYSTEMIC BLOOD-PRESSURE IN DOGS, Critical care medicine, 26(1), 1998, pp. 126-131
Objective: To investigate whether prostaglandin E-1 (PGE(1)) directly
inhibits hypoxic pulmonary vasoconstriction in dogs. Design: Prospecti
ve, longitudinal study. Setting: University research laboratory. Subje
cts: Six mongrel dogs in vivo. Interventions: The left thorax of anest
hetized and ventilated dogs was opened and the left lower lobe was sep
arately ventilated, The tip of the thermodilution pulmonary artery cat
heter was introduced into the left lower lobe pulmonary artery, The le
ft lower robe was ventilated with hyperoxic (95% oxygen and 5% CO2) or
hypoxic (95% nitrogen and 5% CO2) gas. By manipulating the occluders
placed on both pulmonary arteries, blood flow in the left lower lobe w
as regulated, Continuous pressure-flow plots for the left lower lobe w
ere then obtained, Measurements and Main Results: Measurements include
d continuous pressure flow plot generation, thermodilution cardiac out
put and blood flow in the left lower lobe, and blood gas analysis, Alv
eolar hypoxia of the left lower lobe caused blood flow in the left low
er robe to decrease from 371.8 +/- 63.4 to 95.0 +/- 23.4 mL/min and sh
ifted the pressure-flow plot to the right, with a decreased slope and
with an increase in the pressure axis intercept, Subsequently, systemi
c venous infusion of PGE(1) at a rate of 0.3 mu g/kg/min had no effect
on the pressure-flow plot configuration, blood flow in the left lower
lobe, pulmonary vascular resistance, systemic vascular resistance, an
d Pao(2). However, there was a decrease in the pressure-axis intercept
of the pressure flow plot, Infusion of PGE(1) at a rate of 3.0 mu g/k
g/min (high-dose) during hypoxia reduced pulmonary vascular resistance
and systemic vascular resistance by 19% and 25%, respectively, and re
turned the pressure flow plot toward normal while blood flow in the le
ft lower lobe increased to 122.6 +/- 21.0 mL/min. Consequently, Pao(2)
decreased from 270 +/- 31 to 144 +/- 32 torr (36.0 +/- 4.1 to 19.2 +/
- 4.3 kPa). Conclusion: High dose PGE(1) essentially inhibits hypoxic
pulmonary vasoconstriction, at the expense of a deterioration in pulmo
nary gas exchange and systemic blood pressure in dogs.